Device and method for assembling large space structures

ABSTRACT

An automated assembly, maintenance, and repair system for the construction of a large space structure. The space structure comprises a plurality of trusses and truss junctions that in turn are made up of a plurality of individual struts and nodes. The truss assemblies are progressively built by an assembler trolley as the trolley crawls along the constructed truss. The trolley comprises a forward crawler and a rear crawler joined by an articulated coupler. The crawlers are carried along the structure by belt transports incorporating grippers that engage the truss structure at the nodes. Manipulator arms for strut and node assembly are located on the forward crawler, and the majority of control, power, and communication systems are located in the rear crawler. Cargo canisters filled with component parts for constructing the space structure are carried by the forward crawler. The space structure configuration is determined by the arrangement of the individual struts and nodes during the assembly process.

BACKGROUND OF THE INVENTION

Early space structures were fully assembled on earth prior to launchinginto space, and their size was limited to the cargo volume of the launchvehicle. Subsequent structures comprised ingenious folded, compressed,or rolled high-density assemblies that would unfurl, deploy, or expandupon arriving in space to form structures displacing a volume many timeslarger than the original stowage volume provided by the launch vehicle.

More sophisticated and complex structures for earth orbit deploymenthave been developed. Some such structures are to be manufactured inspace by roll forming and welding of densely packaged spooled stripstock, usually of aluminum, thermoplastic graphite epoxy, or othercomposite material. Pulltrusion or rolltrusion forming at elevatedtemperature is used on the composite materials, and cold roll forming isthe usual forming method employed on aluminum.

For structures of increased size, which require volumes of materialbeyond the capabilities of these methods to produce, a new technique isrequired that will utilize the technologies and advantages of theseprior assembly and deployment methods and will additionally possess thecapabilities to produce structures vastly larger in size. Such atechnique must be highly mechanized and automated to have theperformance and cost effectiveness required of it.

SUMMARY OF THE INVENTION

The present invention is an automated assembly, operation, maintenance,and repair system for a large space structure using programmed,computer-controlled, man-supervised automated equipment. The spacestructure comprises a plurality of trusses and truss junctions, eachtruss being made up of a plurality of individual struts and nodes. Thetruss assemblies are progressively built by an assembler trolley as thetrolley crawls along the constructed truss.

The trolley comprises a forward crawler and a rear crawler joined by anarticulated coupler. The crawlers are carried along the structure bybelt transports incorporating grippers that engage the truss structureat the nodes.

Manipulator arms for strut and node assembly are located on the forwardcrawler, and the majority of control, power, and communication systemsare located in the rear crawler. Cargo canisters filled with componentparts for constructing the space structure are carried by the forwardcrawler. The space structure configuration is determined by thearrangement of the individual struts and nodes during the assemblyprocess.

The rear crawler may also contain a man support system so that crewmenmay come aboard to assist in the construction or make necessary repairs.It may also carry spare struts, nodes, and manipulator arms which, ifrequired, are removed and installed by the manipulator arms on theforward crawler of a companion trolley.

The size of the structure to be fabricated in space is unlimited, sincethe trolley is capable of accepting the resupply of structural componentparts from an orbiting cargo vehicle which may shuttle back and forthfrom earth to orbit.

The space structure will provide for the mounting of solar arrayblankets, solar or microwave reflector surfaces, focal point supportstructures and bolt-on components as for example, attitude controlsystem, scientific instruments, and various electronic communication,computation, and control devices.

It is an object of the invention to provide synergistically compatiblestructures and an autonomous, self-regulating assembler device that maybe monitored, supervised, and when necessary operationally modified byremote sensing and control.

It is an object of the invention to provide structural truss-framearrangements that permit the assembler trolley to both assemble thestructure and then have access to any part of the structure to deliverand attach add-on components or to dismantle, modify, or repair thestructure.

It is an object of the invention to provide a light-weight structure,wherein reaction loads from the assembler trolley are reacted only atspecific hard points for efficient distribution into the structure.

Another object of the invention is to provide a method for assemblingthe structure while the trolley is moving at a constant rate such theinertia loads imposed on the assembled structure during the manipulationof components are held below the design limits of the structure.

Another object of the invention is to provide autonomous and remotelymonitored/controlled sensor systems that may stop the motion of thetrolley so that corrective procedures may be instituted bypre-programmed and/or man-in-the-loop activities.

Another object of the invention is to provide struts and strutattachment nodes that may be efficiently stowed in and deployed fromcanisters carried on the assembler trolley, said canisters being capableof replenishment from a cargo vehicle.

Another object of the invention is to provide an assembly device whichhas significantly reduced power requirements to those required forsystems utilizing in-orbit material forming, brazing, or welding.

Another object of the invention is to provide an assembly device whichrequires no large jigs or fixtures for assembly operations.

It is also an object of the invention to provide struts and strut nodesthat are nestable to permit efficient high-density storage in easy tohandle canisters.

The above and other objects and advantages of the invention will appearmore fully hereinafter from a consideration of the following descriptiontaken together with the accompanying drawings, wherein one embodiment ofthe invention is shown by way of example. It should be understoodhowever, that the drawings are for the purposes of illustration only andare not to be construed as defining or limiting the scope of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein like reference characters designate like partsthroughout the various views:

FIGS. 1, 2, and 3 are perspective views of typical large structuresassembled by the disclosed method.

FIG. 4 is an enlarged view of a portion of a structure takensubstantially in the area indicated by circular section-line 4 of FIG.1.

FIG. 5 is an enlarged view of a single structural bay takensubstantially at the area indicated by circular section-line 5 of FIG.4.

FIG. 6 is a perspective view of an expanded strut.

FIG. 7 is a perspective view of a compressed strut.

FIG. 8 is a partial view of the open isogrid structure of a strut takensubstantially at the area indicated by circular section-line 8 in FIG.7.

FIG. 9 is a partial view of a center portion of the strut takensubstantially at the area indicated by circular section-line 9 in FIG.6.

FIG. 10 is a partial view of the strut oval end taken substantially atthe area indicated by circular section-line 10 in FIG. 6.

FIG. 11 is a partial view of the flat end of a strut taken substantiallyat the area indicated by circular section-line 11 in FIG. 6.

FIG. 12 is a cross section of the center strut area taken substantiallyfrom a plane indicated by line 12--12 in FIG. 9 showing the strutpartially compressed.

FIG. 13 is a cross section of the strut taken in the same area as FIG.12 showing the strut in the fully expanded condition.

FIG. 14 is a perspective view of a fixed geometry strut having a hatcross section.

FIG. 15 is a perspective view of a structural nodes positioned asindicated by circular section-line 15 in FIG. 5.

FIG. 16 is a series of cross sections of the node spring legs takensubstantially from a plane indicated by line 16--16 in FIG. 15.

FIG. 17 is a view of a stack of structural nodes positioned as indicatedby circular section-line 17 in FIG. 5.

FIGS. 18 through 20 show the junctions of different numbers of trussstructures coming together to form a structural joint, and are takensubstantially at the areas indicated by circular section-lines 18, 19and 20 respectively in FIG. 4.

FIG. 21 is a top view of the junction shown in FIG. 18.

FIG. 22 is a side view of the junction shown in FIG. 21.

FIG. 23 is a top view of the junction shown in FIG. 19.

FIG. 24 is a side view of the junction shown in FIG. 23.

FIG. 25 is a top view of the junction shown in FIG. 20.

FIG. 26 is a side view of the junction shown in FIG. 25.

FIG. 27 is a perspective view of a structural node used at trussjunctions.

FIG. 28 is a perspective view of the assembler trolley.

FIG. 29 is a perspective view of the crawler coupler shaft.

FIGS. 30 through 34 are perspective views showing the maneuvering of theforward crawler relative to the rear crawler.

FIG. 35 is a perspective view of the forward crawler.

FIGS. 36 through 39 are enlarged partial views of the transport belt andgrippers of the forward crawler showing operations of the node grippers.

FIG. 40 is a perspective view of the assembler trolley within a trussstructure.

FIG. 41 is an enlarged cross-section of the forward crawler primarystructure taken substantially from a plane indicated by line 41--41 inFIG. 35.

FIGS. 42 and 43 are views of the struts and nodes storage canister.

FIG. 44 is a perspective view of a tubular telescoping manipulator arm.

FIG. 45 is a perspective view of the rear crawler.

FIGS. 46 through 56 indicate the series sequential steps of the forwardcrawler assembling a truss structural bay.

FIG. 57 is a perspective view of a strut inspection device.

FIG. 58 is a perspective view of a telescoping triangular trussmanipulator arm.

FIGS. 59 and 60 are schematic views of the dog-disc pitch drive beltsystem.

FIG. 61 is an enlarged view of the bottom surface of the manipulator armworking end showing the dog-disc tool.

FIG. 62 is a partial side view of the manipulator arm and includes across-section through the dog-disc tool.

FIG. 63 is a cross-section of the manipulator arm taken substantiallyfrom a plane indicated by line 63--63 in FIG. 61.

FIG. 64 is a partial side view of the manipulator arm taken in the areaof the cross-section line 64--64 of FIG. 63.

FIG. 65 is a cross-section of the manipulator arm taken substantiallyfrom a plane indicated by line 65--65 in FIG. 61.

FIG. 66 is a view of the dog-disc tool in several prime positions.

FIGS. 67 through 72 indicate the parallel sequential steps of theforward crawler assemblying a truss structural bay.

FIGS. 73 and 74 are views of the trolley wherein the forward crawler isassemblying a truss junction.

FIG. 75 is a view showing the assembler trolley passing through a trussjunction.

FIG. 76 is a schematic presentation of the control and monitor systemsfor the assembler trolley.

FIG. 77 is an end view of an alternate embodiment of the forward crawlerlocated within the structural truss.

FIGS. 78 through 81 show the assembly sequence for a platform structurecomprising a plurality of side-by-side disposed triangular trusses.

FIG. 82 is a perspective view of the structural node utilized in thestructure shown in FIGS. 78 through 81.

FIGS. 83 and 84 show a method of deploying a working surface on thecompleted truss structure.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, FIGS. 1, 2, and 3 illustraterespectively a planar space-deployed structure, a cylindrical parabolastructure, and a paraboloidal dish structure. In order to appreciate themagnitude of these structures certain basic dimensions are shown by wayof example. These structures may cover tens or hundreds of square milesin area, having no counterpart here on earth.

FIG. 4 is an enlarged view of that portion of the planar structure ofFIG. 1 shown by view line 4. Again a dimension of the structure is shownby way of example of the magnitude of the structure.

FIG. 5 is an enlarged view of that portion of the truss structure ofFIG. 4 shown by view line 5. There are again illustrated severalstructural dimensions, which are only by way of example, so that bycomparing FIGS. 1, 4, and 5 one may gain an appreciation andunderstanding of the relationship of the basic truss to the overallstructure.

Referring again to FIG. 4, it is seen that the upper and lower faces ofthe structure are composed of trusses 10 forming coincident equilateraltriangular patterns. These faces are joined by triangulated web trusses11 to in effect form a space frame isogrid structure. Because of itsconfiguration, and because all members perform equally well in tensionand compression, the structure has excellent structural efficiency andstability. This is particularly true with respect to torsional loading,about an axis parallel to the structural plane, as well as bending andin-plane loading. Structures employing guy wire cross members areinherently not as efficient, since the wires contribute to structuralstrength or stiffness only when loaded in tension.

In FIG. 5 it is seen that the basic truss structure is of a triangularcross section, and is constructed of a plurality of tapered struts 12,each strut having a circular cross section which tapers to a flatsection at each end which terminates on nodes 13. Each of the threesides of a truss bay comprises a rectangle bounded by four struts andone diagonal strut. This produces six strut terminatives per node 13,thereby allowing all nodes to be of the same shape and configuration.

FIG. 6 shows a tapered strut 12 in detail. The strut comprises two conicmonocoque shells joined at their bases to define a taper in bothdirections from the mid section. Portions of the shell are relieved andlightened with an open isogrid hole pattern, shown in greater detail inFIG. 8. Each half 14 and 15 of the conic shell is attached together bymeans of a longitudinal piano hinge 16, shown in greater detail in FIG.9.

FIG. 7 shows the tapered strut 12 in the flat stowed position. Eachconical half shell 14 and 15 (see FIG. 9) is compressed flat forstorage, the movement accommodated by a combination of the springcharacteristics of the conical shell sections and the piano hinge 16.The shell halves 14 and 15 are extremely light gage material and may beconstructed of any suitable metal such as aluminum or stainless steel,or any suitable composite material such as for example, graphite epoxy.The diametrically opposed longitudinal piano hinges 16 and spring actiondue to pre-forming of the strut material allows the strut to assume theexpanded state when released from the stowed condition.

The relatively large diameter at the center of the strut produces lowstowed-state stresses and permits a circular cross section to developwhen released from the stowed state. Near the ends of the strut thereduced diameter causes higher stowed-state stresses and allows for onlyan oval cross section in the deployed state, which is more clearly seenin FIG. 10. It is necessary that transitions take place betweendifferent cross sections along parts of the strut length. Therefore, thehinges 16 include some small localized end play to eliminate hingebinding during strut expansion. Actually, because of the small departureof the hinge line from a straight line and the available elasticity inthe thin gage strut material, the binding action is tolerable even if noend play is included. Deployed state roundness at the ends of the strutcan be achieved or maximized by the staggered slots 17, shown in FIG.10.

FIG. 11 shows a plurality of strut ends in their relative positions in astack of stowed struts. Both ends of the strut are flat and each endincludes two circular holes 18 for attachment to the nodes 13. Locatedadjacent to the two node mounting holes 18 is a keyway 19. Also in FIGS.6 and 7 it will be noted that along the strut length there are otherperiodically space keyways 19. As will be explained in more detaillater, these keyways 19 are used to hold the struts in their stowedstate. The keyway in the flat part of the strut ends is used to handlethe strut during and after expansion, and it will be noted that thekeyways are alternately clocked 90 degrees on adjacent struts in thestowed position as shown in FIG. 11.

Mounted longitudinally to the conical shell at the mid point of thestrut is a plurality of spring clips 20. These clips bridge the twotransverse slots between the bases of the two conical shells, and whenthe shells are compressed these clips are disengaged, as shown moreclearly in FIG. 12. When the strut is fully expanded the clips 20 engagethe strut shell, as shown in FIG. 13, to provide structural continuitybetween the two conical portions of the strut.

For stowage the struts are stacked side by side in the compressedposition to achieve high packaging density. As indicated the keyways 19are clocked 90 degrees between successive struts in the stack. As willbe subsequently explained this is done to implement the retaining,release and engagement of struts in the structural assembly process.

A fixed geometry strut 21 is shown in FIG. 14. It is of a generallyhat-shaped cross-section and tapers towards each end from a maximumcross section at strut mid point. Both ends of the strut are flat andinclude the two node attachment holes 18. This fixed geometry strut 21does not have the structural efficiency and column/beam stability of theexpandable strut 12, and while it must be heavier than the expandablestrut for comparable performance, it is simpler to fabricate, stack anddeploy. Because no prestresses exist in the stacked condition of thefixed geometry struts 21, the number of keyways 19 for hold downpurposes may be less than those needed in the deployable strut 12. As inthe deployable strut, excess cross-section is reduced by isogrid holepatterns.

Tapered struts, of the fixed geometry 21 and expandable types 12 areinherently more efficient than constant cross-section struts. This isespecially true of structures primarily designed for stiffness. Theexpandable strut 12 is the preferred embodiment for most structuralapplications and is the type shown in all figures except FIG. 14.

FIGS. 15 and 17 illustrate enlarged views of two nodes 13 taken fromFIG. 5. The node in FIG. 15 has six spring leaf legs attached to a solidhub 22 containing a keyway 19. As seen in FIG. 16, each leg consists oftwo spaced leaves 23 and 24, two locating pins 25 attached to leaf 23that engage the strut ends 12, and a lead-in flare 26 that minimizes thenecessary alignment between the strut and node at assembly. As indicatedin FIG. 16 after the strut end 12 is inserted between the spring leaves23 and 24 it must be tilted to pass over the pins 25 to be finallyassembled.

FIG. 17 shows a plurality of stacked nodes 13. As in the case of thestruts, the keyways 19 are clocked 90 degrees between successive nodesin the stack. A shaft mounted dog 27 retains the stacked nodes when thedog is crosswise to the keyway. When the dog 27 is rotated intoalignment with the keyway 19 the node at the top of the stack can beremoved while the node directly below it is inhibited by the dog 27.This is also the type of release and containment system used for thestruts, and its use will be described hereinafter.

Note that the lead-in flares 26 of leaves 23 and 24 are staggered alongthe node legs. This allows the space between the leaves to be occupiedby the alternately located flares 26 so that nodes may be stacked flushfor stowage.

FIGS. 18, 19 and 20 illustrate three different truss junction forms thatmay be utilized in various structures of the type illustrated in FIG. 4.Further, FIGS. 21 and 22 are plan and elevation views respectfully ofthe truss junction shown in FIG. 18; FIGS. 23 and 24 are similar viewsof the truss junction shown in FIG. 19; and FIGS. 25 and 26 are plan andelevation views of the truss junction shown in FIG. 20. The arrangementsof struts forming the truss junctions provide structural continuitybetween trusses terminating on the junctions, while at the same timethey provide uninhibited communication between the internal crosssections of these trusses. This is essential for free movementthroughout the entire structure of a trolley, to be later described, andbecause of these unique truss junction characteristics it is possiblefor an assembler trolley to pass through the junction when crawlingbetween the insides of two trusses terminating on the junction. Theassembler trolley assembles both the trusses and junctions by movingalong the inside of the completed truss structures. When the assembly iscompleted the trolley is then capable of crawling to any part of theassembled structure.

As was previously described, the nodes 13 in each individual trussstructure are of the same arrangement of all points along the truss.However the strut nodes located in the truss junctions may be of adifferent arrangement than the nodes 13 used in the individual trusses.A typical truss junction node 28 is shown in FIG. 27. For specific trussjunctions the node will vary in the number of additional legs and theirorientation, however any node arrangement must be of a shape that willallow high density stacking. The most efficient stacking results fromstacking similar or comparable nodes in common stacks. In some casesmixed stacking of different nodes is possible without loss of stackingefficiency.

An important feature of all nodes 13 and 28 is the solid hub 22 to whichthe spring leaf legs 23 and 24 are attached. These hubs are configuredto be engaged by tong type grippers from both the inside and outside ofthe truss or truss junction structure. Because of this importantfeature, engagement between the assembler trolley and the structure canbe primarily limited to the node hubs 22, and the trolley can functionon either the inside or outside of the trusses and truss junctions.Since the nodes are also the strongest, most reinforced, parts of thestructure they are the best places to apply the necessary trolleyactuation loads. A coincident common point of intersection is providedby the geometry for all lines of force acting on the spring leaf legsand the hub of each node.

The assembler trolley 30 is shown in a perspective view in FIG. 28. Thetrolley performs three primary functions:

It stows the structural component parts in high density pre-packaged,easy-to-handle, canisters;

It assembles the component parts into a structural arrangement, eitherby means of a pre-programmed scenario or by a remote control/monitorsystem;

And it is used for access to any part of the structure to make repairs,modifications, or install non-structural items such as, for example,solar blankets, reflector surfaces, scientific instrumentation, attitudecontrol devices, and electronic packages.

The trolley 30 comprises a forward crawler 31 and a rear crawler 32which are joined together by a coupler shaft 33. The forward crawler 31mounts twelve manipulator arms 34 and 35, four manipulator arms disposedon each of the three exterior side surfaces of the forward crawler 31.The three manipulator arms 34 at the forward end and the threemanipulators 34 at the rear end of the forward crawler 31 have singlestage axial extension capability, while the six manipulator arms 35located in the mid area of the crawler, two per side, have two stageextension capability.

The twelve manipulator arms, 34 and 35, have rotary drives disposed atthe base end where attachment is provided to the forward crawler 31.Linear drives are also provided to retract and extend the manipulators,permitting up to a three to one change in reach. All manipulator armdrive functions are preprogrammed and numerically controlled. The totalnumber of manipulator arms disposed on the forward crawler 31 is afunction of the desired assembly rate of the trolley 30. As fewmanipulator arms as two per side, a total of six on the forward crawler,31, may accomplish the assembly task. However the maximum assembly rateis attained when approximately seven manipulator arms are disposed oneach side of the crawler, a total of twenty-one manipulator arms locatedon the forward crawler 31. This optimum number of manipulator armsapplies to the triangular truss described herein, and other structuralforms may require more or less manipulator arms. The functions performedby the manipulator arms and two embodiments of these arms will bedescribed in greater detail later herein. It should be understood thatif desired to accomplish certain assembly functions, manipulator armsmay also be located on the rear crawler 32.

In FIG. 29 is shown a more detailed view of the coupler shaft 33, whichconnects forward crawler 31 with rear crawler 32. The coupler shaft 33is connected to the rear crawler 32 by means of a universal joint 36,having an azimuth pivot pin 37 and an elevation pivot pin 38. Rotationaround the azimuth pivot 37 is controlled by azimuth drive motor 39which drives a gear head which mates with gear teeth contained onazimuth pivot pin 37, the gear drives not shown. In a like mannerrotation about the elevation pivot 38 is controlled by elevation drivemotor 40.

Located near the forward crawler 31 is a second universal joint 42,having a similar arrangement to the first universal joint 36. Rotationaround the azimuth pivot 43 is controlled by azimuth drive motor 45, androtation around the elevation pivot 44 is controlled by elevation drivemotor 46. The distance between universal joint 36 and universal joint 42is variable by means of shaft 48 telescoping within larger diametershaft 49. Displacement of inner shaft 48 is controlled by a linear drive50, which comprises a linear drive motor 51 that drives a pinion whichin turn is engaged with a gear rack mounted on the shaft 48, in aconventional rack and pinion arrangement. For clarity of FIG. 30 none ofthe gear drive arrangements are shown, since all are of a conventionalarrangement well known by those skilled in the art. The linear drive 50also provides a keying function so that no axial rotation of inner shaft48 is possible relative to outer shaft 49.

Attached to the forward universal joint 42 is a rotary drive 52,comprising a drive motor 53 that drives a gear that is fixedly attachedto the end of a forward shaft 54 such that drive motor 53 may rotateshaft 54 around its longitudinal axis. The forward shaft 54 is shown inFIG. 30 fully telescoped within the forward crawler 31. The shaft 54 maybe extended from the crawler 31 by means of a linear drive 55 that isattached to the forward crawler 31. The linear drive 55 functions in thesame manner as linear drive 50.

From the foregoing it may be seen that the distance between the forwardcrawler 31 and rear crawler 32 is variable by means of linear drive 50extending or retracting inner shaft 48 within outer shaft 49. Further,it may be seen that the forward crawler 31 may be displaced in azimuthrelative to rear crawler 32 by actuation of azimuth drive motor 39and/or azimuth drive motor 45, and in a like manner displacement inelevation may be accomplished by elevation drive motor 40 and/orelevation drive motor 46. Longitudinal rotation of forward crawler 31relative to rear crawler 32 is accomplished by actuation of rotary drive52. And finally, it will be observed that the distance of the forwarduniversal joint 42 from the forward crawler 31 is variable by means oflinear drive 55 extending and retracting the forward shaft 54 within theforward crawler 31.

Thus, if inner shaft 48 is extended the two crawlers move apart as shownin FIG. 30 and 31. If azimuth drive motor 39 and elevation drive motor40 of rear universal joint 36 are actuated the forward crawler 31 willbe displaced in azimuth and elevation from rear crawler 32, as shown inFIG. 32. The longitudinal axis of the forward crawler 31 will beparallel with the longitudinal axes of outer shaft 49, inner shaft 48,and forward shaft 54, and will be skewed relative to the longitudinalaxis of rear crawler 32. If the azimuth drive motor 45 of the forwarduniversal joint 42 is driven an equal amount in the opposite directionto azimuth motor 39, and elevation motor 46 is driven an equal amount inthe opposite direction to elevation motor 40, the forward crawler 31will remain disposed in azimuth and elevation relative to rear crawler32, but the longitudinal axes of the two crawlers will be parallel asshown in FIG. 33. The forward crawler 31 may now be moved forward fromthe forward universal joint 42 by actuating the forward linear drive 55which extends forward shaft 54, as shown in FIG. 34. The forward crawler31 may also be rolled about the forward shaft 54 by actuating the rotarydrive 52. In this regard, it may be understood that the movements of thecrawlers about their three major axes may be described as ROLL(controlled by rotary drive 52) PITCH (controlled by elevation motors 40and 46) and YAW (controlled by aximuth motors 39 and 45).

The FIGS. 30 through 34 illustrate only one example of the displacementmaneuvering of forward crawler 31 relative to rear crawler 32, but fromthis example it should be clear what the displacement capabilities are,and it should be understood that all necessary drives may be operatedsimultaneously if desired to effect a smooth transition to the newposition of crawler 31, rather than the stepped displacements describedin the example.

FIG. 35 is a more detailed view of the forward crawler 31, wherein itmay be seen that a pair of pulleys 56 are mounted at opposite ends ofeach edge formed by two intersecting side surfaces of the crawler. Atotal of six pulleys 56 are so located on the crawler. A runaround, orcontinuous, belt 57 is wrapped around each pair of pulleys 56, and restsin a belt guide 58. The belt guide 58 is attached to the crawler by aplurality of belt guide supports 59. Attached to each belt 57 are nodegrippers 60, one of which is shown in more detail by the enlarged viewin FIG. 36.

FIG. 36 illustrates the node gripper 60 that is located on the lowerbelt 57 near the forward pulley 56 of FIG. 35. It will be seen that belt57 is of a generally hexagon cross section and is guided on the fourside surfaces by belt guide 58. The inner surface of the belt 57comprises a plurality of serrations or what may generally be describedas rack gear teeth 62. These teeth 62 engage mating teeth on the pulleys56, each of which is driven by a motor 64, best seen in FIG. 35. Thesemotors, 64 like all the drive motors utilized on the assembler trolley30 are direct current stepping motors that are servo controlled bypre-programmed controllers.

The node gripper 60 comprises a spreader bar 66 and a pair of gripperjaws 68, one pivotally mounted to each end of spreader bar 66. Thegripper jaws are rotated by means of the up and down stroke of jawactuator rod 70 within the jaw actuator guide 71, down motion causingthe jaws to open and upward motion causing the jaws to close. At the topend of the jaw actuator rod 70 is a spherical surface 72 which functionsas a cam follower, and at the bottom end of the rod 70 is a secondspherical-surfaced cam follower 73. The actuator guide 71 is fixedlymounted within the belt 57 and carries the node gripper 60 along thebelt as the belt is driven from one pulley 56 to the other pulley 56. Atpoints along the inside top surface of the belt guide 58 are linearramps which serve as cams to force the jaw actuator rod 70 down to openthe jaws 68. As the node gripper 60 approaches a structural strut node13, see FIGS. 5 and 15, the lower cam surface 73 of jaw actuator rod 70is forced upward by contact with hub 22 of strut node 13, therebycausing the gripper jaws 68 to close and grip the strut node 13. Thismay best be seen in FIGS. 37, 38 and 39.

In FIG. 37 is shown a node gripper 60 attached to the lower portion ofbelt 57. This node gripper 60 is in the opened position and is locatedon the belt in the same manner as the gripper shown in FIG. 36. On theupper portion of belt 57 is another node gripper 60 in the closedposition, since the actuator rod 70 was forced up by the ramp in beltguide 58. This normally is the position for gripping a strut mode, suchas is shown in more detail in FIG. 38. Here it is seen that the jaws 68have closed and locked on the hub 22 of a strut node 13. It should benoted that in this particular instance the crawler is within the trussstructure 10 and is gripping the inside surface of node 13. As waspreviously stated, the trolley may travel inside of a truss structure 10or on the outside of a truss, and in FIG. 39 is shown a strut node 13being engaged on the outside surface by a gripper on the upper portionof belt 57. The same arrangement for a gripper 60 located on the lowerportion of belt 57 is also shown, and it should be clear that thetrolley may travel externally either above or below a truss structure.

In FIG. 40 the trolley 30 is located within the truss structure 10. Itwill be noted that the rear crawler 32 has three belts 57 and sixpulleys 56 of the same general arrangement as the forward crawler 31.The three node grippers 60 of the rear crawler 32 are gripping the threestrut nodes 13 located at the truss station designated as 113, and thethree node grippers 60 of the forward crawler 31 are gripping the threestrut nodes 13 located at the truss station designated as 213. Thetrolley may continue through the truss structure 10 by driving in unisonall the belt drive pulleys 56, and as it passes the next set of strutnodes 13 a second set of node grippers 60 on the belts 57 will grip thenodes while the grippers now locked will open. Another method to movethe forward crawler 31 in the truss structure is to release the nodegrippers at truss station 213, while the rear crawler 32 maintains agrip on nodes at truss station 113, and then extend or retract thecrawler coupler shaft 33.

FIG. 41 shows a perspective view and cross-section of the primarystructure of forward crawler 31. At the approximate geometric center ofthe crawler is the longitudinal guide 76, within which the forwardcontrol shaft 54 (FIG. 29) moves fore and aft. The forward crawlerstructure is shaped to form six long rectangular cargo compartments 78and six triangular cross-section control shaft raceways 80. Disposedwithin each of the control raceways 80 are a plurality of coupling driveshafts 82 which reach approximately the full length of the raceways 80and are journalled for rotation therein. Spaced along the bottom surfaceof each argo compartment 78 are a plurality of drive couplings 84 whichare engaged by means of miter gears to the coupling drive shafts 82 sothat rotation of the shafts 82 will rotate the associated couplings 84.

FIGS. 42 and 43 are perspective views of a cargo canister 90 which issized to fit within the canister cargo compartment 78 of the forwardcrawler 31. Stowed within the canister 90 are snugly stacked struts 12and strut nodes 13. At the bottom of each stack of struts 12 and nodes13 is located a stack advance plate 92. A plurality of lead screws 94pass through the keyways 19 of struts 12 and nodes 13, through a stackadvance plate 92, and through the bottom wall of the canister 90,terminating at the bottom end with a drive coupling 96 which is shapedfor engagement with a mating coupling 84 in the cargo compartment 78 ofthe forward crawler 31. At the top end of each lead screw 94 is mounteda dog 27 which is shaped to pass through keyway 19 when properlyoriented, but to retain the struts 12 and nodes 13 at all other rotatedpositions. The stack advance plate 92 is threaded for engagement withthe lead screw 94 so that rotation of the lead screw causes the plate 92to advance. It should be noted that no lead screw or dog is disposedwithin the keyway located at either end of the struts.

The thread pitch of lead screw 94 is a function of the thickness of anindividual strut 12 or node 13. If the keyways 19 are alternatelyclocked as shown in FIG. 11, then the dogs 27 must alternately rotate450 degrees once to align with a keyway 19 and rotate 270 degrees thenext time to align with the next clocked keyway, thereby requiring arepeated cycling of 270 degrees rotation followed by 450 degrees andthen 270 degrees rotation, etc. The average rotation of the lead screwis 360 degrees per thickness of strut, but the maximum and minimumrotations must be accounted for in the thread pitch and thecompressability of the stack of struts or nodes. Such an arrangementrequires only two configurations of struts or nodes, that is keyways at0 degrees position and 90 degrees position. Another arrangement requiresfour configurations of struts and nodes, wherein keyways are clocked at0 degrees, 90 degrees, 180 degrees and 270 degrees. With thisarrangement the lead screw 94 is rotated 450 degrees each cycle to alignthe dog 27 with the next keyway 19, thus eliminating the variablerotation required by the two position keyway arrangement. Eitherarrangement may be utilized with satisfactory results. The function ofthe lead screw 94 and dog 27 is to allow only one strut 12 or node 13 ata time to be removed from the canister.

Thus it may be seen that the forward crawler 31 is capable of carrying alarge quantity of struts and strut nodes in the six canisters 90 stowedin the six cargo compartments 78.

If one man can assemble a given structure in one-hundred hours, the taskmay be described as a one-hundred manhour task. However, this does notnecessarily imply that the task could be accomplished with thearithmetic equivalent of one-hundred men working for one hour. Analysismay reveal however that there does exist an optimum number of men toassign to the task to complete it in the minimum number of manhours. Forexample, three men may accomplish the task in thirty hours, therebyexpending a total of only ninety manhours. In a like manner atime-motion kinematic analysis was conducted, directed at the assemblyprocedure utilizing various numbers of manipulator arms 34 and 35disposed on the forward crawler 31. It was concluded that a minimum oftwo manipulator arms per side, six per crawler, could assemble the basictriangular truss structure 10. It was also concluded that maximumutilization of the crawler is obtained when seven manipulator arms aredisposed on each of the three sides of the crawler. The configuration ofthe manipulator arms differ for these two conditions, the two arms perside arrangement being less complicated than the seven arms per sidearrangement. Thus, if time is not critical it may be worth sacrificingtime in order to utilize a simpler manipulator arm arrangement. Laterherein the assembly method utilizing two manipulator arms and the methodutilizing seven manipulator arms will both be described. Before this maybe done however it is first necessary to describe each of the twomanipulator arm embodiments.

FIG. 44 is an enlarged view of a double extending manipulator arm 35.The shoulder joint 102 attaches to the forward crawler 31 and comprisestwo drives, a shoulder roll drive motor 103 which rotates a bevel pinionthat is meshed with a bevel ring gear attached to the crawler side, andan elevation drive motor 104 which rotates the manipulator arm about themotor 104 shaft centerline. Extension and retraction of the arm lengthis accomplished by three telescoping tubes 106, 108 and 110. The middletube 108 is moved in and out of outer tube 106 by means of the lineardrive 111, while inner tube 110 is moved in and out of middle tube 108by means of linear drive 112. These two linear drives 111 and 112operate in the same manner as the linear drive 50 on the crawler couplershaft 33 shown in FIG. 29. Functionally the outer tube 106 may bedescribed as a sleeve, the middle tube 108 as a first arm telescopingwithin sleeve 106, and the inner tube 110 as a second arm telescopingwithin the first arm 108.

The wrist joint of the manipulator arm comprises a clevis fitting 114,which supports a trunnion mounted wrist block 115. The clevis fitting isrotated around the longitudinal centerline of tube 110 by means of therotary drive 116 which operates in the same manner as the shoulder rolldrive 103. The wrist block 115 is rotated around its trunnion by meansof drive motor 117. The wrist block 115 is bored along its major axis,perpendicular to the trunnion centerline, to accept the shaft of drivemotor 118. Fixedly attached to the end of the shaft of drive motor 118is a backup disc 120 and dog 27. The backup disc is spaced from the doga distance approximately equal to the thickness of a strut 12 or node13. The dog-disc may be arranged other than shown, wherein the dog 27and keyways 19 are of other matching geometric shapes, such astriangular or rectangular for example. The dog is bevelled on theleading edge to reduce the engagement tolerance with a matching keywayin a strut or node. The manipulator arm removes struts and nodes fromthe canisters 90, carries them to the truss structure and releases themwhen installed in their proper positions. The dog-disc 120 is typicallyrotated in 90 degree increments to first engage and then disengage thekeyways 19 in the struts and nodes. As in the case of the crawlercoupler shaft assembly 33 the manipulator arm motors are direct currentstepping motors which are pre-programmed and numerically controlled.

FIG. 45 is a cutaway view of the rear crawler 32, wherein the majorcompartment 121 is crew quarters. Located in the rear bulkhead is an airlock 122 which is for crew transfer in and out of the crawler. Atransparent port hole 123 is located in the forward bulkhead, and aplurality of remote operated television cameras 124 are disposed aroundthe forward bulkhead for visual observation of the forward crawler 31and the structure assembly procedure.

The long triangular shaped compartment 125 directly above the crewcompartment is provisioned with spare parts such as pulleys 56, belts57, manipulator arms 34 and 35, coupler shaft 33, and spare structuralstruts 12 and nodes 13. The compartment 126 located below the crewcompartment floor houses the navigation, communication, and telemetryelectronic equipment. Batteries and fuel cells 128 are located to theright of the crew compartment 121, and on the left side is located thepower conditioning systems 130. The numerical control systems 132 arelocated above the batteries, and the environmental control systems 134,utilized to condition the crew compartment and all electronic systems islocated near the rear bulkhead. Thus, it may be seen that the rearcrawler 32 functions as the command center for the assembler trolley,while the forward crawler 31 performs the cargo carrying and structuralassembling functions. Both crawlers 31 and 32 and the interconnectingcoupler shaft 33 work cooperatively to perform the trolley transportfunctions, primarily by means of the traveling belts 57 and nodegrippers 60.

FIGS. 46 through 56 show the primary sequential events in the assemblyof one bay of the truss structure 10. For clarity in these figures therear crawler 32 and the interconnecting crawler coupler shaft 33 are notshown, but it should be understood that the rear crawler 32 is firmlyattached to the inside of the truss structure 10 by means of its sixgrippers holding on to three nodes at one truss station and three morenodes at a second truss station and is supporting and guiding theforward crawler 31 by means of the coupler shaft 33. Further, it shouldbe understood that each of the manipulations by the two arms 35 on thenear side of the forward crawler 31 are being simultaneously done bymanipulator arms 35 on the other two hidden sides of the forwardcrawler.

In FIGS. 46 and 47 the forward manipulator arm 35 removes a structuralnode 13 from the canister 90 and carries it to the node gripper 60located at the forward end of the transport belt 57. The node grippersare spaced on the transport belt at precisely the structuralnode-to-node distance of truss structure 10. At this particular time theforward gripper is located on the lower portion of the transport belt,not having as yet passed over the forward pulley 56. The gripper willcarry the node along as it continues traveling with the transport belt.

It will be seen that the last bay of the truss structure has not beencompleted, lacking the three truss station or cross-member struts. Therear node grippers of the crawler are gripped to the end nodes, butsince the cross-member struts are not in place the nodes, which areconnected to the ends of the longitudinal struts only, are not capableof providing support to the forward crawler. The forward crawler issupported by the crawler coupler shaft 33, cantilevered from the rearcrawler 32.

FIGS. 48, 49 and 50 illustrate the installation of the cross-memberstrut. As was previously described, the stacks of struts and nodes arerestrained in the storage canister by lead screw mounted dogs. The leadscrews pass through keyways in the struts and nodes, the keyways beingclocked 90 degrees between the successively stacked struts and nodes. Torelease a strut the dogs are rotated to align with the long dimension ofthe keyways. The top strut can then be removed, but the next strut inthe stack is prevented from being released, because the keyway in it isclocked to interfere with the dog. Before a strut is released from thecanister it is first gripped by the manipulator arms by means of thedog-disc tool 120 engaging the end keyway of the strut, the end strutkeyway not having a lead screw passing therethrough. When eachmanipulator arm has engaged the keyway on its end of the strut thecanister dogs are rotated and the strut is released.

Before a node is released the dog on the operative manipulator arm isbrought into alignment with the dog retaining the node stack from whichthe node is to be released. The manipulator arm dog is clocked to allowthe subsequently released node to pass directly onto it. When this hashappened the manipulator arm dog is clocked 90 degrees to engage thenode. The manipulator arm then delivers the node to its assemblyposition. Separate keyways may also be provided in each node for use bythe manipulator arm exclusively, such as those provided on each end ofthe struts if it is so desired.

In FIG. 49 the strut is being inspected. As was previously described,the struts are stored flat, and spring action of the strut causes it tobecome round after release from the canister. One of the inspections isto determine that the strut has properly expanded to the full roundcondition. In FIG. 57 the device for making this inspection is shown. Atrack fitting 136 and fixed jaw 137 are attached to the side of theforward crawler. Slideably mounted within the track 136 is a moveablejaw 138, which may be moved back and forth in the track by means of alead screw that is rotated by stepping motor 140. A displacement sensor141 is disposed on the track fitting 136 to determine the strutdiameter. After the strut is placed on the fixed jaw 137 by themanipulator arms, the movable jaw 138 slides into position. The moveablejaw 138 is driven by a torque limited drive. Sensors are included todetermine when this limit is exceeded to indicate incomplete strutexpansion. If the strut has not properly deployed and action of the jawson it does not cause deployment, several remedial actions may be taken:several axial force reversals can be applied by the manipulator armscarrying the strut; with the jaws 137 and 138 engaged, small bendingmoments can be induced at the strut center by the manipulator arms; andthe strut can be axially rotated and displaced with the jaw 138 backedoff to lightly hold the center of the strut. Should a strut not passinspection after these actions an abort sub-routine is commenced fordisposal of the strut. If space permits, it may be placed in the storagecompartment 125 in the rear crawler 32 for analysis of the failure modeor for later repair.

In FIG. 50 the cross-member strut is being inserted into the spring legsof the truss nodes. After this strut is aligned with the appropriatenode legs it is manipulated to pry open the legs, wedge over thelocating pins 25 in the node and achieve installation as previouslydescribed and shown in FIG. 16. Small fore-and-aft and side-to-sideshaking forces are applied to jog the strut to assure completion of apossibly incomplete installation. This closes-out or completes the trussbay structure. It will be seen that as the manipulator arms carried outthe functions shown in FIGS. 46 through 50 the crawler has movedforward, and the nodes installed on the transport belt 57 have movedaround the forward pulley 56 and now are on the top portion of the belt.

All of the truss assembly operations are performed while the crawler ismoving forward at a constant velocity. Constant velocity is an essentialfeature of the system for several important reasons. The assembly timewould be greatly increased if start-stop movement of the crawler wasused. Of even more importance are the weight and power considerations.The power requirements for braking and accelerating the trolley would besignificantly higher than the constant velocity requirements. Theinertia forces imposed on the nodes by the node grippers to react pitch,roll, and yaw inertia moments of the crawlers when braking oraccelerating would be of sufficient magnitude to require beef-up of thetruss structure, resulting in an unsatisfactory weight increase. Bothcrawlers and the interconnecting coupler shaft would likewise increasein weight. Normal stopping and starting distance for the trolley is oneto one and a half structure bay lengths.

In FIGS. 51, 52 and 53 the longitudinal strut is installed. The removingof the strut from the canister and the inspection of the strut is thesame as previously described. The rear end of the strut is then insertedinto the end node 13 of the last completed truss bay while the forwardend of the strut is inserted in the node 13 being carried by the nodegripper on the transport belt. Immediately after this operation iscompleted the aft node gripper passes by a cam mounted on the belt guidewhich releases the gripper as previously described, and the node gripperpasses over the rear pulley.

In FIGS. 54, 55 and 56 the diagonal strut is installed. The crawler hasreleased its grip on the last nodes of the closed-out bay and hasprogressed into the incompleted bay. The node on the forward end of thelongitudinal strut is still retained by the belt mounted gripper as thecrawler continues moving forward. The diagonal strut is removed from thecanister, inspected, and inserted into a node at each end as waspreviously described. The crawler continues to move forward by means ofthe rear crawler moving forward within the completed truss structure bygripping and releasing structural nodes, the transport belts on bothcrawlers working in precise unison, until the forward crawler reachesthe position shown in FIG. 46. The assembly sequence shown in FIGS. 46through 56 is then repeated.

Referring again to FIG. 42, which shows the cargo canister, it will beobserved that manipulator arm indexing shoulders 142 are located on thetop edge of the canister 90 at each stack of nodes and at each end ofthe stacks of struts. These index shoulders 142 serve the function ofguiding the manipulator arm dog-disc tool to the final keyway engagementposition. Without the index shoulders 142 it would be necessary for themanipulator arms to have significantly greater positioning accuracy. Itshould be understood that other indexing means may be used such as forexample notches in the top surface of the canister. The end of themanipulator arm searches out the indexing shoulder or notch 142 andrests upon it. In this position the manipulator dog-disc tool 120 may bemoved normal to the plane of the stowed strut as well as in a directionparallel to this plane and perpendicular to the strut axis. Positionalhunting maneuvers in these two directions will readily locate themanipulator dog-disc tool in its final desired position.

In the preceding assembly method the various steps were conducted one ata time in a series procedure. In order to increase the speed of assemblyit is necessary to resort to a parallel procedure in which various stepsare conducted simultaneously. This is necessary because the speed atwhich each step is performed is limited to a maximum that keeps allstarting and stopping inertia loads of the manipulator arms as well asthe crawler below the design allowables of the structure. In order toaccomplish a parallel procedure it is necessary to utilize a moresophisticated manipulator arm having more maneuverability to handlestruts in a manner that prevents collisions. Secondly, it is necessaryto locate all drives, including those for actuating the dog-disc, closeto the base end of the arm where they will produce minimum inertialoads. This will not only reduce the weight of the arm structure andcrawler support structure, but will significantly reduce the powerrequired for actuating the arm. It should be understood that such an armmay also be utilized in the two arm arrangement previously described.

FIG. 58 is an overall perspective view of a manipulator arm 200. The armcomprises two triangular shaped telescoping truss structures, an arm 202which is slideably mounted within a sleeve 204. An extension-retractionmotor 206 drives a continuous run-around belt 208 which moves within thesleeve 204 and is connected by clamp 209 to the base end of the arm 202to effect telescoping movement of the arm 202 within the sleeve 204. Thesleeve 204 is rotatably mounted to a shoulder joint 210 and is rotatedabout its longitudinal axis by the roll drive motor 212. The sleeve 204is elevated up and down by an elevation drive motor 214 rotating pinion216 that meshes with a sector gear 218. The shoulder joint 210 isrotated about an axis perpendicular to the side surface of the forwardcrawler by means of a train drive motor 220 rotating a pinion 222 thatmeshes with a train gear 224.

Located at the working end of arm 202 is the dog-disc 226 which isrotated by means of a belt drive connected to dog-disc roll motor 228.The dog-disc 226 is also rotatable about an axis perpendicular to oneside of the arm 202 by means of a belt drive connected to dog-disc pitchmotor 230. For clarity the belt drives for dog-disc roll and dog-discpitch are not entirely shown in the figure, but will hereinafter beshown and described.

In FIG. 59 is shown a schematic presentation of the dog-disc pitch beltdrive arrangement. The pitck drive motor 230 is rotating drive pulley232 in a counter-clockwise direction. The drive pulley 232 is arrangedto have gear teeth that mesh with mating teeth on the inner surface ofthe first stage pitch belt 234 which is wrapped around a portion ofidler pulley 236 to form a continuous belt arrangement. Meshed with theteeth of first stage pitch belt 234 is a transfer pulley 238. The motor230 and the two pulleys 232 and 236 are all mounted on sleeve 204.Integral with transfer pulley 238 is a second transfer pulley 240 thatis located in arm 202 and meshes with and drives the second stage pitchbelt 242 that wraps around pitch drive pulley 244 mounted in arm 202.The result of this arrangement is that a counter-clockwise output ofdrive pulley 232 in sleeve 204 is transferred by means of transferpulley 238 and 240 to the arm 202 and results in a counter-clockwiserotation of the dog-disc pitch shaft 246.

In FIG. 60 is shown a schematic presentation of the dog-disc pitch drivearrangement that is the same as FIG. 59 except that arm 202 has extendedfrom sleeve 204. If the first stage belt 234 remains stationary as thearm 202 is extended from sleeve 204, the transfer pulley 238 must rotateclockwise as it "walks" along first stage belt 234 from its position inFIG. 59 to that shown in FIG. 60. The result of this "walk" of pulley238 would be to produce a clockwise rotation of the dog-disc pitch shaft246. To prevent the extension of arm 202 to effect the pitch attitude ofthe dog-disc it is therefore necessary that pitch drive motor 230 rotatein a counter-clockwise direction to drive first stage belt 234 atprecisely the same rate as the "walking" rate of transfer pulley 238.This is accomplished by a negator signal being sent to motor 230 that isof the same sign and of proportional value as the signal sent toextension-retraction motor 206, (FIG. 58).

The dog-dics roll belt drive system is arranged in the same way as thedog-disc pitch belt drive system, just described, so that a negatorsignal is also sent to the dog-disc roll motor 228 whenever theextension-retraction motor 206 receives a command signal.

FIG. 61 is a view of the bottom surface of the arm 202 at the workingend showing the dog-disc tool 226. The dog-disc is journaled in a wristfitting 248 and terminates with a bevel gear 250 that meshes with asecond bevel gear 252. The wrist fitting 248 is in turn journaled inbearing 254 which is mounted in the arm 202.

FIG. 62 is a side view of the arm 202 and includes a cross-sectionthrough the dog-disc joint, where the wrist fitting 248 is more clearlyseen. Fixedly attached to the wrist fitting 248 is the second stagepitch drive pulley 244 that is engaged by second stage pitch belt 242for rotating the wrist fitting 248 in its support bearing 254. Disposedwithin the wrist fitting 248 are two bearings 256 that support a gearshaft 258 which is fixedly attached to a second stage roll drive pulley260 that is engaged by second stage roll drive belt 262. Thus it can beseen that the wrist joint comprises a coaxial drive arrangement whereinrotation of the drive pulley 260 causes the dog-disc 226 to be displacedin roll angle by means of the two bevel gears 250 and 252, and thedog-disc to be displaced in pitch angle when the pitch pulley 244 isrotated. If the roll pulley 260 is held stationary and the pitch pulley244 rotates the wrist fitting 248 the large bevel gear 250 will rotateas it "walks" around the small bevel gear 252, causing a pitch inducedroll of the dog-disc 226. This induced roll must be negated by a counterrotation of the roll pulley 260. This is accomplished by a biasingsignal being sent to the dog-disc roll motor 228 (FIG. 58) whenever acommand signal is sent to the dog-disc pitch motor 230.

At the base end of arm 202 are located the dog-disc transfer pulleys.The second stage pitch belt 242 passes around transfer pulley 240, whilethe first stage pitch belt 234 is engaged on one side by pitch transferpulley 238 as previously shown in FIG. 59. In a like manner the secondstage roll belt 262 passes around transfer pulley 264 and pulley 268engages one side of first stage roll belt 270. The two roll transferpulleys 264 and 268 have their axis clocked 60 degrees with respect tosecond stage dog-disc roll drive pulley 260 at the working end of arm102, thus requiring a 60 degree twist in belt 262.

FIG. 63 more clearly shows the arrangement of the dog-disc roll transferpulleys 264 and 268. Located in arm 202 is a bearing 272 which supportstransfer pulley 264 so that it is disposed within the arm 202 andsupports the pulley 268 so that it is disposed externally to arm 202 andwithin the sleeve 204, so that it is accessible to the first stage rolldrive belt 270 that is powered by the dog-disc roll drive motor 228. Abelt hold-off guide 274 is located on the external surface of the arm202 and disposed between the belt 270 and pulley 268 to assure that thebelt does not contact the pulley on that side. Diametrically opposite islocated a belt engagement guide 275 which bears against the back of belt270 to assure positive engagement of the belt with the pulleys 268.These two guides 274 and 275 are more clearly shown in FIG. 64.

In FIG. 65 it may be seen that the pitch transfer pulleys 238 and 240are supported from arm 202 by two bearings 276 such that transfer pulley240 is disposed within arm 202 and accessible to second stage pitchdrive belt 242 which wraps around pulley 244 at the working end of arm202, and transfer pulley 238 is disposed in sleeve 204 to be accessibleto the first stage pitch drive belt 234 that is powered by the pitchdrive motor 230 mounted to the base end of sleeve 204.

From the foregoing it should be understood that a runaround belt driveis located on each of the three inside surfaces of the manipulatorsleeve 204. Each of the belts pass around a power driven pulley locatednear the shoulder end of the sleeve 204, one per side, each powered byits respective motor (extension-retraction 206, dog-disc roller 228, anddog-disc pitch 230), and over one of the three idler pulleys, onemounted on each of the side surfaces of sleeve 204 at the far end.Further, the two dog-disc control belts each engage moveable transferpulleys that transfer belt motion to the dog-disc 226 located on theworking end of arm 202 at any extension position of the arm 202 relativeto sleeve 204. The dog-disc 226 has more than 360 degrees capability inpitch and roll, and the manipulator sleeve 204 has more than 360 degreescapability in train and roll.

FIG. 66 is a side view of the working end of manipulator arm 200 takenwhile looking along the external surface of forward crawler 31. Thedog-disc tool 226 is perpendicular to the crawler surface 31 in the"normal" position, designated by the letter N. The dog-disc must berotated clockwise approximately 30 degrees to be perpendicular to thesurface of the top strut 12 in the strut stack retained in canister 90,see FIGS. 41 and 42. This is the position of the dog-disc for picking upa strut or node from the canister and is designated by the letter P.From the "pickup" position, P, the dog-disc is rotated counterclockwiseapproximately 210 degrees to the "flipped" position, designated byletter F. In the flipped position the dog-disc is holding the strut awayfrom the crawler surface so that other manipulator arms 200 may passbelow the strut, between the strut and crawler surface, withoutcollision with the strut.

As was previously described, a strut 12 is removed from the canister 90by two manipulator arms 200, one engaged to each end of the strut 12. Ifthe two manipulator arms 200 are perpendicular to the strut, i.e. thetwo manipulator arms 200 are parallel to one another, the strut may beflipped simply by rotating the dog-disc 226 in pitch the required amountas shown in FIG. 66. However, if the manipulator arms are not parallelto one another and perpendicular to the strut at the time a strut is tobe flipped, the coordinated movement of the two manipulator arms employsthe use of all drive motors in order to keep the two dog-disc axesparallel to each other as they rotate in pitch to the flipped position.

In FIG. 67 seven manipulator arms 200 are located on one of the externalsurfaces of the forward crawler 31. Each manipulator arm has a specificassignment. One manipulator arm 200N transport nodes from the canisterto the node gripper, two manipulator arms 200D handle the diagonalstruts, two arms 200L handle longitudinal struts, and two arms 200Chandle cross-member struts. Struts are removed from the canister in thefollowing sequence:

All arms are positioned below the two arms 200D. With the dog-disc inthe pickup position (FIG. 66) the two arms 200D remove the diagonalstrut from the canister and flip the diagonal strut.

The two arms 200L move below arms 200D and remove and flip thelongitudinal strut.

The two arms 200C move under arms 200D and 200L, and after thelongitudinal strut has passed over the arms 200C the arms 200C removeand flip the cross strut.

FIGS. 68 through 72 show the assembly sequence. In FIG. 68, manipulatorarm 200N removes a node from the canister and moves it to the nodegripper 60 which is traveling along transport belt 57. Arm 200N bringsthe node up to the same speed and direction of the node gripper andholds it in position for the gripper to acquire the node, whereupon thearm 200N releases the node.

In FIG. 69, the two arms 200D position the diagonal strut and insert thetop end into the truss mounted node. The rear arm 200D then releases thediagonal strut, while the lower and forward arm 200D continues to holdon to the diagonal strut.

In FIG. 70, the two arms 200L position the longitudinal strut and insertthe rear end into the top truss mounted node. The rear arm 200L thenreleases the longitudinal strut, while the forward arm 200L continues tohold on to the forward end of the longitudinal strut.

In FIG. 71, the arm 200L continues to hold on to the forward end of thelongitudinal strut until the node being moved along transport belt 57arrives in position, whereupon arm 200L inserts the end of thelongitudinal strut in the node and then releases the longitudinal strut.In the same manner arm 200D inserts the forward end of the diagonalstrut in its transport belt retained node and then releases the diagonalstrut.

In FIG. 72, arms 200C position the cross strut and insert it in theupper and lower nodes, whereupon the belt mounted grippers 60 releasethe nodes, and the sequences shown in FIGS. 68 through 72 are repeated.

It should be understood that the sequences shown in FIGS. 67 through 72may overlap so that more than one sequence is underway simultaneously.For example, the strut removals shown in FIG. 67 include the flipping ofstruts which would normally be accomplished while the manipulator armshave started to execute their delivery motions. With this parallelmethod of assembly the work periods of each manipulator arm aresufficiently long that arm extension and slew rates are sufficiently lowto minimize inertia loads, while the transport speed of the crawler, andtherefore the speed of assembly, may be significantly faster than theseries method, using only two manipulator arms, that was previouslydescribed and shown in FIGS. 46 through 56.

It should be understood that truss shapes other than triangular may beassembled using either the series or parallel method of construction,and that the number of sides of the forward and rear crawler may bevaried accordingly. For example the crawler cross-section may be asquare, rectangle, pentagon, hexagon, or octagon, and the trussstructure may be of a similar shape. Additionally, it should be clearthat the crawler may have fewer working sides than the sides of thecompleted truss structure. For example, the triangular truss may beassembled by a triangular crawler having manipulator arms disposed ononly one side, and after completing a first side of the truss thecrawler would roll 60 degrees and start assembly of the second trussside.

Because the seven manipulator arms arrangement locates each arm near toits maneuvering area, only a single stage telescoping arm is necessary,however if fewer manipulators are employed and the reach must beincreased a second telescoping arm may be located within the first arm,and all drive functions transferred from the first arm to the second armin the same manner as the arm and sleeve arrangement previouslydescribed.

In the case where an assembly step is not properly concluded, asindicated by instrumentation or visual observations, it would benecessary to stop the assembly operations. First, the manipulator armsrelease any struts or nodes that are attached to the completed trussstructure. Braking force is applied to the assembler trolley to arrestthe forward motion. The stopping distance should be less thanapproximately one and a half structural bays so that the rear crawlerdoes not disengage from the truss structure. The trolley direction isreversed until the correct crawler position relative to the unfinishedstructural bay is obtained. Each released strut or node is reacquired bythe forward crawler, and subroutine corrective programs are enlisted toconduct corrective maneuvers. If these corrective steps do not reinstatethe assembly procedure an abort procedure is initiated, or manualoverrides are initiated. In certain cases it may be desirable to bringthe forward crawler to a quicker halt than would be accomplished by thepreceding braking method. Such a requirement would cause the attendanttrolley deceleration forces to rise above what the structure strengthwould normally allow. Faster than normal braking of the forward crawleris possible to the extent that the crawler coupler shaft 33 is extendedat the time of braking. The coupler shaft may be foreshortened at acontrolled rate that would first impose only the forward crawlerdeceleration forces to the structure. After the forward crawler hasstopped the rear crawler is decelerated. The peak braking force appliedto the structure would be the same as during a normal trolley stop, andthe nominal stopping distance of the total trolley would also be thesame in order for the energy formula to balance, however the forwardcrawler could be stopped in a shorter distance, since a portion of thetotal trolley stopping distance is utilized in closing the distancebetween the forward and rear crawlers.

At the end of a completed truss a truss junction may be assembled, asshown in FIGS. 73 and 74. The trolley is brought to a stop with theforward crawler 31 positioned beyond the completed truss structure. Inthis position the movements of manipulator arms 200 and articulations ofthe coupler shaft 33 are coordinated to assemble an entire trusssection, wherein one manipulator arm acts as a fixturing device byholding a node while other manipulator arms install struts in thefixtured node. In some truss junction embodiments the node grippers 60on the crawler transport belts 57 serve as the node fixturing device. Inthis manner the forward crawler maneuvers to assemble the trussjunction, in some cases the forward crawler attitude may be as much as90 degrees from the position of the rear crawler which is gripping thepreviously completed truss. When the truss junction is completed theforward crawler commences to assemble the new truss, and the trolleyproceeds into the new truss as shown in FIG. 75. In this particulartruss junction it is necessary that the forward crawler roll 60 degreesabout its longitudinal axis while passing through the assembled trussjunction, followed thereafter by the rear crawler which also rolls 60degrees as it passes through the truss junction.

Another example of fixturing is when a truss structure is begun. Themanipulator arm 200N places a node in the node gripper as shown in FIG.68. The transport belt 57 carries the node forward around the forwardpulley 56 to the top portion of the belt and then toward the rear untilthe node arrives at the position of the node shown in FIG. 72. At thistime there would be three nodes, one in each of the three grippers, eachgripper located on one of the three transport belts 57, that would belocated in the station plane of the truss. These three nodes arefixtured by the forward crawler until the three cross-member struts areinserted in the nodes as shown in FIG. 72. A structurally stable portionof the truss is now completed, and the assembly procedure can now beginin the sequence shown in FIGS. 67 through 72.

Use of two manipulator arms with coordinating motions while grasping astrut requires a sophisticated control system. Force sensors allowoptimum coordination by slaving one of the arms so that it is partiallydriven by the other arm through the strut. The force levels of the armsare limited so as to not damage the strut.

Each step of the assembly process requires control of closure speeds,loads, and accurate positioning. The control system is aided by overrideclutches mounted on the manipulator arms as well as sensors fordetermining force, proximity and touch.

The overall control system is shown in FIG. 76. The control is basicallyautomatic and can be supervised by man, with computer backup, on theground and/or in orbit. A central control computer exercises executivecontrol functions. Each side of the forward crawler contains its ownlocal controller with its digital computer, A/D, D/A, analog drives,compensation networks, and microprocessors. Splitting the forwardcrawler control functions into groups allows fast response between itemsneeding close synchronization. Additionally, the manipulator arms have amicroprocessor in their direct control loops to provide reflexive actionfor each arm.

Thus, it should be understood that the herein disclosed inventioncomprises an assembled truss structure arrangement and an assemblertrolley that carries, handles, and assembles structural elements andother components to the very structure on which it is crawling. Thetrolley and the structural arrangement are compatible for a wide rangeof autonomous, self-regulating functions in situ that are monitored,supervised, and as necessary modified by remote sensing and control.

A typical truss has a triangular cross-section and is constructed withtapered struts terminating on nodes. The three sides of each truss bayhave similarly oriented diagonal struts. This results in six strutterminations per node and allows all truss nodes to have the sameconfiguration. Other trusses as well as tetrahedral structures havinginternal clearances for an assembler trolley may also be constructed.

The arrangements of struts forming the truss junction provide structuralcontinuity and fixity between trusses terminating on the junctions. Atthe same time, they provide uninhibited communication for assemblertrolley turning space between the insides of trusses terminating onthem.

The assembler trolley assembles the trusses and truss junction by movingalong the inside of these structures by means of belt transportsincorporating grippers that engage the structure at the nodes. The nodehas six springleaf legs attached to a solid hub containing a keyway.Each leg consists of two spaced leaves, two locating tapered pins thatengage the strut ends, and a lead-in flare that facilitates alignment ofthe strut and node during assembly.

An important feature of the nodes is the solid hubs to which thespringleaf legs are attached. These hubs are arranged to be engaged bytong-type grippers from both the inside and outside of the truss ortruss junction structure. As a consequence, the assembler trolley canfunction on either the inside or outside of the trusses or trussjunctions. And, since the nodes are the strongest and most reinforcedpart of the structure, they provide ideal load distribution points forthe assembler trolley support. The assembler trolley induces minimalkick moments into a node since a nearly coincident common point ofintersection exists for all lines of force acting on the legs and hub ofa node.

The assembler trolley comprises forward and rear crawlers joined by anarticulated crawler coupler. Automatically focused TV cameras on therear and forward crawlers monitor assembly operations. In the event of amalfunction, manually controlled backup operations may be carried outwith the aid of these cameras by an onboard crew or ground-based controlstation.

The forward crawler carries prepackaged structural cargo in replaceablecanisters and a plurality of manipulator arms. Each manipulator arm hasshoulder azimuth, roll, and elevation drives. At its working end are twowrist drives; roll and pitch. The linear actuation between shoulder andwrist achieve changes in arm reach. All manipulator arms are releasableand removable by adjacent arms in the event of failure. Those oncooperating assembler trolleys are also programmed for mutual removaland replacement. The store of spare parts on the rear crawler of oneassembler trolley may similarly be made accessible to the forwardcrawler of a companion assembler trolley.

An actuated dog with an integral backup disc is carried at the workingend of the manipulator arm. This dog is used to grasp struts or nodesfor removal from the cargo canisters and to release them when deliveredand installed in their proper assembly positions. The dog is typicallyrotated in 90 degree increments to first engage and then disengage thestrut or node, and where necessary detents may be provided to morepositively engage the strut or node during manipulations.

It should also be understood and apparent to those skilled in the artthat other arrangements, modifications, and applications of thedisclosed invention may be made that are within the spirit and scope ofthe invention. For example, the nodes may not be stored in the samecanister 90 as the struts, but stored in separate node canisters 280 asshown in FIG. 77. The node canisters 280 are located adjacent to thetransport belt 57 and are so disposed that the nodes 13 may be dispensedone at a time directly to the node grippers 60 by means of a lead screwand stack advance plate system similar to that utilized in the strutcanister 90. Such an arrangement would eliminate the node removalfunction of the manipulator arms. For compactness the canisters 280,along with transport belts 57 and their pulleys 56 may be hinged to stowflush with the sides of the forward crawler 31, such as shown in thelower right hand corner of the crawler in FIG. 77.

Many structural arrangements other than those shown in FIGS. 1 through 4may be constructed. For example, a platform structure, such as shown inFIGS. 78 through 80, may be assembled by the assembler trolley 30. Thisstructure comprises a plurality of triangular trusses constructedside-by-side such that adjacent trusses have a common planar trussframe. The platform is constructed by the assembler trolley 30 travelinga serpentine path as it constructs each adjacent truss in a sequenceshown in FIGS. 78 through 80.

In FIG. 78 the assembler trolley constructs three sides 281, 282 and 283of a truss to the desired length using the method previously described.The rear crawler 32 is brought to a stop inside the completed truss suchthat the rear crawler is gripped to the end bay of the completed trusswith the crawler coupler shaft 33 and forward crawler 31 extended beyondthe truss. The two universal joints 36 and 42 (FIG. 29) of the crawlercoupler shaft 33 are then each rotated 90 degrees in a plane normal totruss side 283 to bring the forward crawler 31 into a heading position180 degrees to the rear crawler 32, thus essentially having completed aU-turn.

The forward crawler then begins construction of the two truss sides 285and 286, as shown in FIG. 81, proceeding down this second truss by meansof the extension of the forward shaft 54. After two bays of the secondtruss, comprising sides 283, 285 and 286, are completed the forwardcrawler 31 moves backward to the edge of this second truss. The rearcrawler 32 then moves out of engagement with the first truss structure,whereupon the two universal joints 36 and 42 are each rotated 90 degreesto bring the rear crawler into longitudinal alignment with the forwardcrawler. The forward crawler then moves forward into the second trussand completes the assembly of the second truss.

When the second truss is completed, the forward crawler is then extendedbeyond the second truss and maneuvered into a U-turn in the mannerpreviously described to start the assembly of the next two sides of thethird truss.

The platform structure shown in FIGS. 78 through 80 would require a nodehaving ten legs, which would serve the function of two six-leg nodes 13placed side by side. The ten-leg node 290 is shown in FIG. 82, where itwill be seen that the same shaped keyway 19 is located at theapproximate center of the node hub. It will be observed however thatbecause of the increased thickness of the node hub 22 the keyway 19 doesnot extend completely through the hub. A recess 292 is provided so thatthe hub thickness in the area of the keyway is the same thickness as thehub on six-leg nodes 13, thereby permitting engagement by the samedog-disc tool 226. In FIG. 82 is shown a cross-section of the recess 292and a spring biased button 294 which serves to retain the dog when it isrotated in the recess. The button 294 must be overcome for bothengagement and disengagement of the dog-disc tool with the node. Thisprovides for positive engagement during node maneuvering by themanipulator arm. A simple dimple may also serve this detenting function,and similar detenting devices may be utilized on other nodes as well asthe struts if such are necessary.

It is likewise apparent that other structural shapes such as square, T,L, Z, U and triangular may be utilized for the truss struts with goodresults. Fixed L and U shapes are particularly well suited for efficientstacking in a storage canister. Such struts are less stable andefficient than the expandable strut as a column or beam, but, while theymust be heavier than the expandable strut for comparable performance,they are simpler to fabricate, stack, and deploy. Because no prestressmust be contained in the stacked condition, the number of keyways orholddown points may be less for fixed struts than for the deployablestrut.

Upon completion of the structure the assembler trolley may serve as atransport and material handler by moving on the inside or outside oftrusses. The trolley may also be used to install equipment on thestructure. In FIGS. 83 and 84 the trolley is shown attaching a workingsurface to the structure as an example. The working surface could be,for example, a solar blanket, an aluminized plastic reflector, or a wiremesh microwave beam former and amplifier array. The trolley attachesclothes line type pulleys to one end of a structure, then maneuvers toan opposite end where it attaches the end of a roll of working surfaceto the clothes lines and drives the clothes line until the workingsurface is payed out. The working surface is then attached at eachcorner to a structural node utilizing the node keyway, or to specialfittings attached to the structure for that purpose. The trolley thenmoves forward and the process is repeated. This process is particularlyefficient where two trolleys are utilized, one at each end of theclothes line.

After the working surface has been installed the trolley hasaccessibility to the working surface from inside and outside contiguoustrusses as well as from inside and outside of trusses which support it.This accessibility may be used to repair the working surface as well asinstall power and microwave connections and transmission lines andfinally to assemble and hook up all onboard subsystems.

The previously described arrangements are by way of example to show thatarrangements and applications of the invention, other than the preferredembodiment herein disclosed, will become apparent to those skilled inthe art, and these along with other modifications and applications ofthe disclosed invention may be made by those skilled in the art withoutdeparting from the scope of the invention, the scope limited only by theclaims.

I claim:
 1. An assembler trolley for the construction of a structurecomprising:a forward crawler; a rear crawler; a crawler coupler, saidcoupler telescopically connected between said forward crawler and saidrear crawler; a plurality of transport belts mounted on each of saidcrawlers; gripping means mounted on said transport belts for grippingsaid structure; and manipulator arms disposed on at least one of saidcrawlers for maneuvering elements of said structure.
 2. The assemblertrolley of claim 1 wherein said crawler coupler comprises;a firstcontrolled movement universal joint; an outer tube having a fixed endand an open end, said outer tube connected at said fixed end to saidfirst universal joint; an inner tube disposed within said outer tube andhaving an external end extending beyond said open end of said outer tubefor telescopic movement within said outer tube; a second controlledmovement universal joint connected to said external end of said innertube; and a forward tube connected at one end to said second universaljoint.
 3. The assembler trolley of claim 2 wherein said crawler couplerfurther comprises:a first driving means for rotating said firstcontrolled movement universal joint about an azimuth axis; a seconddriving means for rotating said outer tube about an elevation axis ofsaid first controlled movement universal joint; a gear rack disposedalong substantially the full length of said inner tube; a pinion gearrotatably mounted to said outer tube and meshed with said gear rack; athird driving means for rotating said second controlled movementuniversal joint about an azimuth axis; and a fourth driving means forrotating said inner tube about an elevation axis of said secondcontrolled movement universal joint.
 4. The assembler trolley of claim 3wherein said crawler coupler further comprises:a keying means forpreventing torsional rotation of said inner tube around the longitudinalaxis of said inner tube relative to said outer tube; and rotary meansfor torsional rotation of said forward tube around the longitudinal axisof said forward tube relative to said inner tube.
 5. The assemblertrolley of claim 1 wherein each of said transport belts comprises:a pairof pulleys, one pulley mounted at each end of said crawler; a runaroundbelt passing around said pair of pulleys; and a driving means forrotating at least one of said pulleys.
 6. The assembler trolley of claim1 wherein each of said gripping means comprises:a spreader barjuxtapositioned parallel to said belt; two gripper jaws, one gripper jawpivotally attached near each end of said spreader bar; and means foropening and closing said gripper jaws.
 7. The assembler trolley of claim1 wherein each of said manipulator arms comprises:a sleeve having aproximal shoulder end and a distal free end; an arm slideably mountedwithin said sleeve for telescopic movement therein, said arm having aworking end extending beyond said free end of said sleeve; a dog-disctool rotatably mounted to said working end of said arm; a first meansfor rotating said dog-disc tool around the longitudinal roll axis ofsaid dog-disc tool; a second means for rotating said dog-disc toolaround a pitch axis perpendicular to said dog-disc tool longitudinalroll axis; a third means for rotating said dog-disc tool around thelongitudinal axis of said arm; and a shoulder fitting attached to saidshoulder end of said sleeve to provide pivotal support of said sleevefor rotation about azimuth and elevation axes.
 8. An assembler crawlerfor transporting and manipulating structural elements comprising:acrawler body structure; a plurality of transport belts mounted on saidbody structure; gripping means mounted on said transport belts forgripping at least some of said structural elements; and a plurality ofmanipulator arms disposed on at least one side of said body structure.9. The assembler crawler of claim 8 wherein said body structure isshaped to define a plurality of canister storage compartments locatedsubstantially within said body structure.
 10. The assembler crawler ofclaim 9 wherein said body structure is further adapted to define acoupler rod support compartment located substantially along thelongitudinal axis of said body structure.
 11. The assembler crawler ofclaim 8 wherein each of said transport belts comprises:a pair ofpulleys, one pulley mounted at each end of said crawler; a runaroundbelt passing around said pair of pulleys; and a driving means forrotating at least one of said pulleys.
 12. The assembler crawler ofclaim 11 wherein said runaround belt is adapted to form a plurality ofgear teeth disposed along an inner surface of said runaround belt, andat least one of said pulleys is adapted to form a plurality of gearteeth disposed around said pulley for meshing with said runaround beltgear teeth.
 13. The assembler crawler of claim 8 wherein each of saidgripping means comprises:an actuator guide fixedly attached to saidtransport belt; a spreader bar juxtapositioned parallel to said belt;two gripper jaws, one gripper jaw pivotally attached near each end ofsaid spreader bar; and an actuator rod slideably mounted within saidactuator guide for opening and closing said gripper jaws.
 14. Theassembler crawler of claim 8 wherein each of said manipulator armscomprises:a sleeve having a proximal shoulder end and a distal free end;an arm slideably mounted within said sleeve for telescopic movementtherein, said arm having a working end extending beyond said free end ofsaid sleeve; a dog-disc tool rotatably mounted to said working end ofsaid arm; a shoulder fitting attached to said shoulder end of saidsleeve to provide pivotal support of said sleeve for rotation aboutazimuth and elevation axes.
 15. The assembler crawler of claim 14wherein said shoulder fitting is adapted to further provide axialsupport of said sleeve for rotation about a roll axis.
 16. A manipulatorarm for maneuvering structural elements comprising: a sleeve having aproximal shoulder end and a distal free end; an arm slideably mountedwithin said sleeve for telescopic movement therein, said arm having aworking end extending beyond said free end of said sleeve; a gear rackdisposed along substantially the full length of said arm; a first piniongear rotatably mounted on said sleeve and meshed with said gear rack; adog-disc tool rotatably mounted to said working end of said arm; ashoulder fitting pivotally attached to said shoulder end of said sleeveto permit said sleeve to rotate about an elevation axis; a clevisfitting rotatably mounted to said working end of said arm for rotationabout the longitudinal axis of said arm; a wrist block shaped to formtrunnions that rotatably mount within said clevis fitting for rotationabout an axis perpendicular to said arm's longitudinal axis; and whereinsaid dog-disc tool is rotatably mounted within said wrist block forrotation about an axis perpendicular to said wrist block trunnions. 17.A manipulator arm comprising:a sleeve having a proximal shoulder end anda distal free end; an arm slideably mounted within said sleeve fortelescopic movement therein, said arm having a base end located withinsaid sleeve and an opposite working end extended beyond said free end ofsaid sleeve; a first runaround belt disposed within said sleeve andconnected to said arm at a point near said base end of said arm formoving said arm telescopically within said sleeve; a wrist fittingrotatably mounted to said working end of said arm for rotation about apitch axis perpendicular to the longitudinal axis of said arm; adog-disc tool rotatably mounted to said wrist fitting for rotation abouta roll axis perpendicular to said wrist fitting pitch axis; a shoulderfitting journaled to said shoulder end of said sleeve to providecantilever support for said sleeve and permit said sleeve to roll aboutthe longitudinal axis of said sleeve; a shoulder trunnion supportfitting rotatably mounted to said shoulder fitting to permit said sleeveto rotate about an elevation axis perpendicular to said sleevelongitudinal axis; and means for rotating said shoulder trunnion supportfitting about an aximuth axis perpendicular to said elevation axis. 18.The manipulator arm of claim 17 further comprising:a first drive pulleyrotatably mounted within said sleeve at said shoulder end of saidsleeve; a first idler pulley rotatably mounted within said sleeve atsaid free end of said sleeve; a second runaround belt disposed withinsaid sleeve and passing around said first drive pulley and said firstidler pulley to define a driving side and a return side of said secondrunaround belt; a first transfer pulley rotatably mounted to said armand disposed between said arm and said sleeve for engagement with saiddriving side of said second runaround belt; a second transfer pulleyfixedly connected to said first transfer pulley for mutual rotation,said second transfer pulley disposed within said arm; a wrist pitchpulley fixedly attached to said wrist fitting for mutual rotation; and athird runaround belt disposed within said arm and passing around saidwrist pitch pulley and said second transfer pulley.
 19. The manipulatorarm of claim 18 further comprising:a first bevel gear fixedly attachedto the end of said dog-disc tool; a wrist roll pulley journalled withinsaid wrist fitting and disposed in said arm; a second bevel gear fixedlyattached to said wrist roll pulley for mutual rotation, said secondbevel gear meshed with said first bevel gear; a third transfer pulleyrotatably mounted to said arm and disposed within said arm; a fourthrunaround belt disposed within said arm and passing around said thirdtransfer pulley and said wrist roll pulley: a second drive pulleyrotatably mounted within said sleeve near said shoulder end of saidsleeve; a second idler pulley rotatably mounted within said sleeve nearsaid free end of said sleeve; a fifth runaround belt disposed withinsaid sleeve and passing around said second drive pulley and said secondidler pulley to define a driving side and a return side of said fifthrunaround belt; and a fourth transfer pulley fixedly connected to saidthird transfer pulley for mutual rotation, said fourth transfer pulleydisposed within said sleeve for engagement with said driving side ofsaid fifth runaround belt.